On Monday, the Department of Agriculture said certain foods including prepackaged wraps and salads that use lettuce from Fresh Express might be affected. The products have sell-by dates from July 18 to 23 and include a chicken Caesar salad sold at Walgreens, a tarragon chicken wrap at Trader Joe's, and a Cobb salad from Kroger. (The full list is here.)

When the cyclospora parasite, transmitted through food contaminated by feces, is then eaten, it can result in an uncomfortable intestinal illness called cyclosporiasis, which can cause diarrhea, vomiting, and weight loss and last for several days or weeks. It is treated with antibiotics and is not fatal.

The parasite can become infectious to other people up to two weeks after being passed in a bowel movement, so it is unlikely that cyclosporiasis is passed directly from one person to another, the Centers for Disease Control and Prevention says.

The FDA said last month that 163 reports of infections had been traced to McDonald's restaurants in Florida, Iowa, Illinois, Kentucky, Minnesota, Missouri, Nebraska, Ohio, South Dakota, and Wisconsin. The outbreak is the second in recent weeks.

McDonald's has said it removed potentially affected salads from restaurants and distribution centers, including about 3,000 in the Midwest.